Plasma has been used in many applications, such as semiconductor processing steps. A conventional plasma processing equipment generates plasma having harsh thermal and/or chemical properties, which causes wear to numerous parts that are exposed thereto during the processing steps. Due to the aggressive nature of the plasma, repeated contact with the plasma may cause one or more of the parts to erode gradually and/or fail abruptly, degrading the performance of the equipment and causing the process result to change over time.
As such, it is important to carefully monitor the states of these parts and change the parts at the appropriate time. If they are changed too soon, the production cost is increased by throwing away the parts which could still be used further. If they are left too long before changing, damage may result to other parts of the equipment leading to additional cost. For instance, eroding an edge ring in a semiconductor processing chamber beyond the safe limit may result in destroying an electrostatic chuck which is a far more costly part. The ideal case is to use the part to the maximum safe limit and no further.
The useful lifetime of each part may be estimated through statistical analysis of degradation and failure when placed in specific environments. However, it is always possible that the part may fail or need to be replaced earlier than expected. Also, in practice, the lifetime of the part may depend on exactly how the equipment is run, which may not be known or closely monitored. Furthermore, it may be necessary to open the equipment to perform an inspection, which is disruptive to production and leads to a certain down-time. Thus, it would be desirable to provide an ability to detect events indicative of the end of useful lifetime, faults, or failure of the part during the operation of the equipment and independent of application in any specific plasma process. It would be further desirable to provide an ability to monitor the state of each part in real time and calling of an alarm when the end of effective operational lifetime of the part is reached.